Re: Possible to disable SpeedStep on battery power?

You can always control manually the frequency. Or do a customized cpufreqd.conf.
To manually control the frequency, there are a number of interface plugins (for gnome, for unity - needs a ppa).
I had to make a customized cpufreq configuration so my tablet wouldn't pass 100C idle... languague is a bit confusing at the start, but works like a charm
(you can, for instance, make the processor stay full power if a given program is running... its quite good)

Re: Possible to disable SpeedStep on battery power?

Thanks for quick response I installed indicator-cpufreq (from http://ubuntuguide.net/change-and-mo...icator-cpufreq), but if I switch it to 2 GHz setting, it immediately falls back to 1 GHz... I wonder if the BIOS is more persistent in saving the battery than full performance?

Re: Possible to disable SpeedStep on battery power?

Tbh what I don't understand is why would you need that? With an ondemand governor (and a proper cpufreqd.conf) it would go automatically to 100% when you need it and stay low otherwise (not much of a point running NOPs on the max frequency... even less on battery).

Anyway, I'm sure you can do what you want by editing the configuration of cpufreqd.

Re: Possible to disable SpeedStep on battery power?

Well I have a reason: I use the laptop mostly with 12 V DC adapter (upping it to 18-19 volts). Apparently Dell laptops do not accept any other power sources but their original AC adapter, and the there's a startup message telling that the adapter is not the right one. I can still use it with 12 volts, but it's always on lower performance mode, that is, running on 1 Ghz instead of 2. I'm not sure if it's the Cpu or the Gpu, but even some graphic/flash intensive web sites make some stutter, and this does not happen when I use mains, 220 V DC.